Load plugins dynamically from source

This patch updates rebar_core to look for missing plugins (i.e. those
that aren't found on the code path at runtime) in a configurable
plugin directory, and dynamically compile and load them at runtime.

By default, the directory "plugins" is searched, although this can be
overriden by setting the plugin_dir in your rebar.config.

6 files changed, 63 insertions, 0 deletions

diff --git a/inttest/tplugins/bad.config b/inttest/tplugins/bad.config
new file mode 100644
index 0000000..23069b8
--- /dev/null
+++ b/inttest/tplugins/bad.config
@@ -0,0 +1,2 @@
+{plugins, [bad_plugin]}.
+{plugin_dir, "bad_plugins"}.
diff --git a/inttest/tplugins/bad_plugin.erl b/inttest/tplugins/bad_plugin.erl
new file mode 100644
index 0000000..77ec01b
--- /dev/null
+++ b/inttest/tplugins/bad_plugin.erl
@@ -0,0 +1,7 @@
+-module(bad_plugin).
+-compile(export_all).
+
+%% this plugin contains numerous DELIBERATE syntax errors
+
+fwibble(Config, _) >
+    file:delete("fwibble.test")
diff --git a/inttest/tplugins/fish.erl b/inttest/tplugins/fish.erl
new file mode 100644
index 0000000..739cb94
--- /dev/null
+++ b/inttest/tplugins/fish.erl
@@ -0,0 +1,5 @@
+-module(fish).
+
+-compile(export_all).
+
+fish() -> fish.
diff --git a/inttest/tplugins/rebar.config b/inttest/tplugins/rebar.config
new file mode 100644
index 0000000..0b9c887
--- /dev/null
+++ b/inttest/tplugins/rebar.config
@@ -0,0 +1 @@
+{plugins, [test_plugin]}.
diff --git a/inttest/tplugins/test_plugin.erl b/inttest/tplugins/test_plugin.erl
new file mode 100644
index 0000000..461247c
--- /dev/null
+++ b/inttest/tplugins/test_plugin.erl
@@ -0,0 +1,8 @@
+-module(test_plugin).
+-compile(export_all).
+
+fwibble(Config, _) ->
+    Pwd = rebar_utils:get_cwd(),
+    Ok = filelib:is_regular(filename:join(Pwd, "fwibble.test")),
+    rebar_log:log(info, "~p:~p in ~s :: ~p~n", [test_plugin, clean, Pwd, Ok]),
+    ok = file:delete("fwibble.test").
diff --git a/inttest/tplugins/tplugins_rt.erl b/inttest/tplugins/tplugins_rt.erl
new file mode 100644
index 0000000..d2ef382
--- /dev/null
+++ b/inttest/tplugins/tplugins_rt.erl
@@ -0,0 +1,40 @@
+-module(tplugins_rt).
+-compile(export_all).
+
+-include_lib("eunit/include/eunit.hrl").
+
+-define(COMPILE_ERROR,
+        "ERROR: Plugin bad_plugin contains compilation errors:").
+
+files() ->
+    [
+     {copy, "../../rebar", "rebar"},
+     {copy, "rebar.config", "rebar.config"},
+     {copy, "bad.config", "bad.config"},
+     {copy, "fish.erl", "src/fish.erl"},
+     {copy, "test_plugin.erl", "plugins/test_plugin.erl"},
+     {copy, "bad_plugin.erl", "bad_plugins/bad_plugin.erl"},
+     {create, "fwibble.test", <<"fwibble">>},
+     {create, "ebin/fish.app", app(fish, [fish])}
+    ].
+
+run(Dir) ->
+    ?assertMatch({ok, _}, retest_sh:run("./rebar fwibble -v", [])),
+    ?assertEqual(false, filelib:is_regular("fwibble.test")),
+    Ref = retest:sh("./rebar -C bad.config -v clean", [{async, true}]),
+    {ok, _} = retest:sh_expect(Ref, "ERROR: Plugin .*bad_plugin.erl "
+                               "contains compilation errors:.*",
+                               [{newline, any}]),
+    ok.
+
+%%
+%% Generate the contents of a simple .app file
+%%
+app(Name, Modules) ->
+    App = {application, Name,
+           [{description, atom_to_list(Name)},
+            {vsn, "1"},
+            {modules, Modules},
+            {registered, []},
+            {applications, [kernel, stdlib]}]},
+    io_lib:format("~p.\n", [App]).